Semiconductor device and manufacturing method thereof

Abstract

An object is to provide a semiconductor device with stable electric characteristics in which an oxide semiconductor is used. The impurity concentration in the oxide semiconductor layer is reduced in the following manner: a silicon oxide layer including many defects typified by dangling bonds is formed in contact with the oxide semiconductor layer, and an impurity such as hydrogen or moisture (a hydrogen atom or a compound including a hydrogen atom such as H2O) included in the oxide semiconductor layer is diffused into the silicon oxide layer. Further, a mixed region is provided between the oxide semiconductor layer and the silicon oxide layer. The mixed region includes oxygen, silicon, and at least one kind of metal element that is included in the oxide semiconductor.

Description

TECHNICAL FIELD[0001]The present invention relates to a semiconductor device including an oxide semiconductor and a manufacturing method thereof.[0002]In this specification, a semiconductor device means all types of devices which can function by utilizing semiconductor characteristics, and an electrooptic device, a semiconductor circuit, and an electronic appliance are all semiconductor devices.BACKGROUND ART[0003]In recent years, a technique for forming a thin film transistor (TFT) by using a semiconductor thin film (having a thickness of approximately several nanometers to several hundreds of nanometers) formed over a substrate having an insulating surface has attracted attention. Thin film transistors are applied to a wide range of electronic devices such as integrated circuits (ICs) and electro-optical devices, and, in particular, thin film transistors that are used as switching elements in image display devices are urgently developed. There exists a wide variety of metal oxides...

AI Technical Summary

Benefits of technology

[0014]The mixed region may have a thickness of 1 nm to 10 nm (preferably, 2 nm to 5 nm). A clearly defined interface is not formed between the oxide semiconductor layer and the silicon oxide layer by provision of the mixed region, whereby hydrogen can be more easily diffused from the oxide semiconductor layer into the silicon oxide layer.

[0022]In the above-described manufacturing methods of a semiconductor device, when the oxide semiconductor film and / or the silicon oxide film is / are formed, it is preferable that an adsorption-type vacuum pump be used for exhaustion in the first treatment chamber and / or the second treatment chamber. For example, a cryopump, an ion pump, or a titanium sublimation pump is preferably used. The adsorption-type vacuum pump is effective to reduce the amount of hydrogen, hydroxyl, or hydride included in the oxide semiconductor film and / or the silicon oxide film.

Problems solved by technology

However, a difference from the stoichiometric composition in an oxide semiconductor arises in a thin film formation process.

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